The invention relates to an auxiliary power steering device of generally conventional construction except for the provision therein of the novel means of effecting steering resistance simulation. Various devices for effecting steering resistance simulation have been known for a long time and are shown, e.g., in U.S. Pat. No. 3,180,233 and French Pat. No. 1,505,333.
In the U.S. patent, the steering spindle is provided with a forked end which can actuate reaction pistons mounted transversely of the spindle axis in the course of a steering operation. The reaction pistons act against system pressure to resist manual force rotation of the steering spindle and thereby a simulated steering resistance or rod reaction to steering is effected. In such construction, the torsion rod is used in a conventional manner for return of relatively rotative valve elements wherein rotation of the steering spindle effects relative rotation to control pressures to and from a double acting cylinder. The reaction pistons are suitably sized and have differential piston surfaces to produce a predetermined steering resistance opposing manual rotation of the steering spindle. Constructions of that kind are relatively bulky and complex and require suitably large housings.
The French Pat. No. 1,505,333, as exemplified in FIGS. 6 and 7 therein, shows a steering spindle operated valve member which terminates in a pair of diametrically opposed notches. In each notch there is a roller trapped between the respective notch and an opposed notch carried in a member connected with the steering spindle through a torsion rod. The notches have curved sides and a series of dish springs are utilized surrounding the torsion rod to maintain resilient axial force on the rollers against the steering spindle. A hydraulic pressure force is provided by a separate piston in a chamber in the steering spindle to effect axial force of the steering spindle against the rollers. Such axial forces must be overcome by manual rotation of the steering spindle to effect road resistance. In that construction production costs are relatively high. Further, deformation and wear of the abutting elements can lead to jamming in view of the pressure forces involved.